Calcified Hofmann’s ligaments as the cause of spinal cerebrospinal fluid leaks associated with spinal ventral dural tears

OBJECTIVE Patients with spinal CSF leaks often have ventral dural abnormalities (type 1 CSF leaks); however, the pathological mechanism for developing dural abnormalities is unknown. The authors investigated whether calcified dural ligaments contribute to the development of ventral dural tears, which cause spinal CSF leaks. METHODS Consecutive patients diagnosed with type 1 CSF leaks who had spiculated spinal lesions between 2010 and 2024 were included. Clinical, radiological, surgical, and histological findings were reviewed. RESULTS Nineteen patients with type 1 CSF fistulas had spiculated spinal lesions (15 men; median age 47 years, range 28–71 years). Spiculated lesions showed a high density on CT, and the median lesion length was 3.5 mm (range 1.6–9.1 mm). Spiculated lesions were consistently located at the center of the ventral dural abnormalities, penetrated the dura mater, and were located in the high thoracic spine (T1–5) in 13 patients (68%) and in the low thoracic spine (T8–12) in 6 (32%). These spinal lesions were connected to the posterior longitudinal ligament, but not to the vertebral body or disc. Histologically, they did not include degenerative osteophytic or discogenic tissues, mostly comprised fibrotic tissues with some calcification, and were consistent with calcified dural ligaments. CONCLUSIONS The anatomical characteristics of spiculated spinal lesions associated with ventral dural abnormalities are consistent with those of calcified dural ligaments, referred to as Hofmann’s ligaments. These ligaments are important for neurosurgeons, neurologists, and neuroradiologists who diagnose and treat type 1 CSF fistulas.